ABSTRACT
<p><b>OBJECTIVE</b>To investigate the role ofCD4+CD25+ T regulatory (Treg) cells, T helper (Th)17cells and interleukin (IL)-6 in the progression of hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF) and determine their value as prognostic markers.</p><p><b>METHODS</b>The Chinese National Knowledge Infrastructure (CNKI), WanFang, Chinese Scientific Journals (VIP), PubMed, Embase and Web of Science databases were searched for English language case-control studies on the relationship between regulatory T lymphocytes and ACLF.The quality of included studies was assessed using the Newcastle-Ottawa scale. The meta-analysis was designed according to the PICOS approach recommended by the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. RevMan software, version 5.1, was used to perform the meta-analysis.</p><p><b>RESULTS</b>Nine case-cohort studies were selected for inclusion in the metaanalysis.The results of the meta-analyses showed that the level of CD4+CD25+ Treg cells was not significantly different between patients with HBV-related ACLF and patients with chronic hepatitis B (CHB) (mean difference (MD)=0.59, 95% confidence interval (CI)-1.68, 2.85, P=0.61) nor between patients with HBVrelated ACLF and healthy controls (MD=1.12, 95% CI:-1.42, 3.66, P=0.39). Thus, it appears that ACLF patients do not have a higher level of CD4+CD25+ Treg cells than CHB patients or healthy controls. However, the ACLF patients did appear to have a significantly higher level of Th17 cells than both the CHB patients (MD=1.73, 95% CI:0.21, 3.26, P=0.03) and the healthy controls (MD=1.62, 95% CI:(0.52, 2.72, P=0.004). In addition, the ACLF patients also had significantly higher level than both the CHB patients (MD=11.69, 95%CI:1.98, 21.40, P=0.02) and the healthy controls (MD=13.17, 95% CI:1.38, 24.95, P=0.03).</p><p><b>CONCLUSION</b>CD4+CD25+ Treg cells may be an important protective factor in the progression and prognosis of HBV-related ACLF, while Thl7 cells and IL-6 may be risk factors for further progression and worsened prognosis.</p>